An intermediate bulk container is usually considered as being a fairly large bag for storing or transporting bulk material, and in particular for comminuted material. Such containers are often provided with lifting straps or handles so that the container may be lifted and transported by mechanical means such as a fork lift truck. Such bags may be circular or generally square in cross-section and may be formed of various grades of material depending on whether the bag is to be reused or is considered to be disposable.
Intermediate bulk material containers are reasonably well known, examples of such being shown in Canadian Pat. Nos. 1,005,023 and 1,007,203, both issued to Nattrass et al. Such containers utilize a heavy grade woven polyester or nylon base with a P.V.C. or other type of coating. All the seams, spout attachments, lift straps and covers are attached to the container by welding the material together. These containers offer the advantages that: they can be made completely waterproof by sealing the filler and discharge spouts off properly; they can be easily repaired by patching over holes with adhesive or by heat welding; spouts can be replaced in the same manner as can the lift straps thereof; they can be provided with different coatings if the product to be contained therein is sensitive to the P.V.C. coating; and because of their heavy duty construction they can be reused many times. The primary disadvantage to this type of container is the cost thereof.
A second type of intermediate bulk container is known as a "one way" or disposable container and is generally made from woven polypropylene or woven polyethylene. The material of this type of container must be sewn. Such containers are difficult to waterproof as well and hence it has been known to obtain a better degree of moisture protection by inserting a polyethylene liner into the container. If the material is loaded in a heated state into the container then a polybutylene liner may be utilized. These liners are satisfactory in most cases and are used extensively for export where the container is not expected to be returned. Such a "one way" container is relatively inexpensive and is light in weight. However, such a container is almost impossible to repair when damaged as there is no adhesive that will satisfactorily hold a patch in place. To sew on a patch means that it would have to be returned to the manufacturer for repair. Also, the reuse factor is limited as it is difficult to replace the liner after use. Furthermore, for sensitive products complete moisture protection is difficult because of the limitations of polyethylene. Canadian Pat. No. 1,005,023 as mentioned above illustrates a container which utilizes such a liner.